[robmgrig]

Do you mean the header bottoms out and won't float? If so sounds like the potentiometer is not adjusted right

 

[robmgrig]

If the cable and everything under the bottom is free then loosen the not on the potentiometer shaft and rotate it back and forth until your header floats. Then fine tune it by rotating it in very small increments until the header comes just off the ground and stops with the height knob set to it's highest position. It should work right then. If the header won't come up at all then your potentiometer may be bad